Disruption of hydrogenase gene for enhancing butanol selectivity and production in Clostridium acetobutylicum

Butanol production by solventogenic clostridia has long been complicated with the formation of acetone as a main byproduct, which causes a low product yield. Here, although some recent attempts failed to engineer the hydrogenase gene hydA in wild-type Clostridium, we successfully disrupted hydA with a plasmid pSY6 in C. acetobutylicum ATCC 55025. The hydA disrupted strain was able to produce 18.3 % more butanol with byproduct acetone decreased by 31.2 %, indicating the inactivation of hydrogenase regulated redox balance for selective inhibition of acetone production. Exogenous supplementation of methyl viologen altered the carbon flux and further reduced acetone formation, with the maximum butanol yield of 0.28 g/g and butanol ratio of 84.0 %, respectively. The similar improvements of butanol yield and ratio were observed with corn stover as carbon source, indicating hydA disrupted strain had the potential for biobutanol production using lignocellulosic biomass. This study provides valuable understanding for regulation of redox and solventogenesis by engineering hydrogenase in Clostridium species towards the advanced production of butanol.

Automated summary

In this study, the disruption of hydA gene in Clostridium acetobutylicum led to increased butanol production and decreased acetone formation. Exogenous supplementation of methyl viologen further improved the butanol yield and ratio. The engineered strain showed potential for producing biobutanol using lignocellulosic biomass.